Method and device for determining a valid lane marking

ABSTRACT

The invention relates to a method and a device for determining a valid lane marking ( 38  to  42; 56, 58 ) with the aid of a camera system ( 16 ) of a vehicle ( 12 ), in particular a road vehicle. With the aid of a camera ( 17 ) of the camera system ( 16 ) several pictures with an image of an area in front of the vehicle ( 12 ) are taken successively as a picture series and image data corresponding to the respective picture ( 30, 54, 66 ) are generated. The image data of at least a part of the pictures ( 30, 54, 66 ) of the picture series are processed, at least a first lane marking ( 38  to  42 ) and a second lane marking ( 56, 58 ) different from the first lane marking ( 38  to  42 ) being detected in at least one picture ( 30 ) of the picture series. A vehicle ( 34 ) driving ahead of the vehicle ( 12 ) is detected in at least two successively taken pictures ( 30, 54 ) and its position (P 1  to P 4 ) relative to the first lane marking ( 36  to  42 ) as well as its position (P 1  to P 4 ) relative to the second lane marking ( 56, 58 ) is determined. Dependent on the positions (P 1  to P 4 ) of the vehicle driving ahead ( 34 ) determined with the aid of the pictures ( 30, 54 ), one of the detected lane markings ( 36  to  42, 56, 58 ) is selected as the valid lane marking ( 56, 58 ).

The invention relates to a method and a device for determining a validlane marking, in which at least a first lane marking and a second lanemarking different from the first lane marking are detected and one ofthese detected markings is selected as the relevant lane marking.

In the prior art, camera-based driver assistance systems are known whichcomprise one or more mono or stereo cameras for observation and analysisof an area in front of the vehicle in the direction of travel. Forcapturing pictures for use in driver assistance systems bothblack-and-white camera systems and color camera systems are known whichcapture pictures of a detection area in front of the vehicle in thedirection of travel and generate image data corresponding to thesepictures. The image data are processed by least one processing unit, thepictures being analyzed and in particular images of objects in thepictures being detected and the objects being classified. In thisconnection, the detection and the classification are usually restrictedto those objects that are relevant for the respective driver assistancesystem. Besides object recognition, the processing unit in particularperforms object tracking, traffic sign recognition of objects classifiedas traffic signs, lane recognition and/or recognition of vehiclesdriving ahead and/or of oncoming vehicles. For lane recognition, usuallythe lane is detected on which the vehicle itself currently moves.Neighboring lanes might be detected as well. In this connection, it ispossible that for example a lane change assistant provides aninformation or a warning to the driver when, for example, the currentlyused lane is left without an activation of the direction indicator. Fordetection of the currently used lane, the respective driver assistancesystem uses the markings that are applied to the lane for lane marking.However, in particular in the case of several overlapping lane markingsit is difficult to detect the currently valid lane marking and to thenuse it for the respective driver assistance system which provides adriver assistance function on the basis of the lane markings. Suchoverlapping lane markings for example occur in areas of roadworks whereat least for some part of the lane a so-called temporary lane marking atroadworks is applied in addition to the original permanent lane markingfor the duration of the road construction work.

In Germany, for example, the permanent lane marking is applied to thelane in the color white and the temporary lane marking is applied in thecolor yellow. Thus, in a roadworks area as well as in an entry area andan exit area of a roadworks area differing lane markings are appliedwhich the human eye usually distinguishes via their difference in color.The colors of temporary and permanent lane markings vary from country tocountry. Methods for distinguishing between temporary and permanentmarkings that are exclusively based on color information are thusdependent on an information as to in which country the vehicle moves.Further, although the use of the temporary marking is standardized,these standards are not always observed so that, for example, also inGermany, a yellow marking may be the relevant marking on the left sideand a white marking may be the relevant marking on the right side atroadworks. Thus, even when using color cameras, the problem may occurthat in bad light conditions, in particular when it rains, thedistinction between the lane markings on the basis of their color is notpossible with sufficient certainty. Further, by means of black-and-whitecameras the colors differences may only be detected by differences inbrightness of the different colors in the picture. In this way, adistinction between valid and non-valid markings is not possible withsufficient certainty. But the use of black-and-white cameras forcapturing pictures for use in driver assistance systems has theadvantage that CMOS image sensors, as used in particular inblack-and-white cameras, allow for a high image resolution and a highgray level resolution of, for example, 4096 gray levels. At present,such a gray level or brightness resolution cannot be achieved withcomparable color sensors. Also the further processing of the image datais considerably reduced in the case of black-and-white images comparedto the further processing of the image data of color images so that theuse of black-and-white cameras in driver assistance systems isadvantageous.

From the document EP 1 653 310 A2, a method for the directional controlof a road-bound vehicle using a camera mounted at a defined position onthe vehicle is known. With the aid of the camera, a permanent lanemarking is detected. Here, marking patterns are detected after enteringa danger zone or an area of roadworks, and a control signal for thetransverse directional control of the vehicle is determined.

From the document DE 103 112 40 A1, a method and a device for thedirectional control of a vehicle is known, in which a distinction ismade between temporary and permanent markings on the lane. Whenevertemporary markings are detected, these are preferably used for thedirectional control of the vehicle.

From the document DE 10 2004 003 848 A1, a method for recognizing markeddanger zones and/or roadworks in the area of lanes is known. Thesemethods use spatial separation images of a detection area of a sensorfor electromagnetic radiation, for example a laser scanner, mounted on avehicle. In the spatial separation images, distinguishing features for adanger zone and/or roadworks are looked for.

It is the object of the invention to specify a method and a device fordetermining a valid lane marking with the aid of a camera system of avehicle, in which the distinction between a permanent lane marking and atemporary lane marking is improved.

This object is solved by a method having the features of claim 1 and bya device having the features of the independent device claim.Advantageous developments of the invention are specified in thedependent claims.

What is achieved by an inventive method and an inventive device is thatwhen selecting the valid lane markings from at least two different lanemarkings, the relative position of the vehicle driving ahead to the twodetected lane markings is taken into account.

It is advantageous to determine the course of movement of the vehicledriving ahead relative to the detected lane markings and to determinewhich of the detected lane markings is the valid lane marking due to thecourse of movement of the vehicle. When deciding which of the detectedlane markings is the valid lane marking, further decision criteria maybe taken into account, such as the position of the own vehicle relativeto the first lane marking and relative to the second lane marking, thesteering angle of the own vehicle or the yaw angle of the own vehiclerelative to the course of the lane and/or the speed of the own vehicle.

It is particularly advantageous to determine a course of movement of thevehicle driving ahead on the basis of at least two, preferably on thebasis of least three pictures captured successively as a picture series.Based on the determined course of movement of the vehicle driving aheadand the courses of the at least two detected lane markings, then one ofthe lane markings can be selected as the valid lane marking.

Further it is advantageous, when each of the lane markings comprises aright marking line and a left marking line and that the positions of thevehicle driving ahead are determined relative to the marking lines.Preferably it is checked whether the course of movement of the vehicledriving ahead corresponds to the courses of the two marking lines withat least a preset probability. The degree of correspondence, i.e. theprobability of correspondence may be determined by using a known patternrecognition method, i.e. a so-called pattern matching method. Themarking lines may be broken lines or solid lines.

Further it is advantageous to select from the at least two lane markingsthe lane marking as the valid lane marking that has a lateral offsettransverse to the traffic direction of the lane for the two determinedpositions, which lateral offset lies within a preset range for bothpositions. Preferably, the positions are determined on the basis of areference position that is vertically under the vehicle longitudinalaxis on the lane. The range may then, for example, be preset with 0.8 mto 1.5 m, preferably 0.8 m to 1.2 m. Alternatively, the lane marking towhich the determined positions of the vehicle driving ahead have anapproximately equal lateral distance or a smaller lateral distance atleast for one determined position may be selected as the valid lanemarking.

Further, it is advantageous to detect a crossing of at least one markingline of one of the detected lane markings and to take it into account inthe determination of the valid lane markings. The crossing of a markingline of one of the two detected lane markings is an indication that thislane marking is not the relevant lane marking.

Preferably a black-and-white camera, in particular a monoblack-and-white camera and a stereo black-and-white camera, are used forpicture capturing. The black-and-white cameras suitable for use in motorvehicles are generally more cost-efficient compared to color camerassuitable for use in motor vehicles, and they generally have a higherresolution and a higher dynamic in the sensing of the brightness levelsso that in particular with a low illumination of the detection area abetter detection of images of objects is possible compared to equivalentcolor cameras.

For determining the valid lane marking, it is particularly advantageousto determine a first degree of correspondence between the course of thefirst determined lane marking and the course of movement of the vehicledriving ahead as well as a second degree of correspondence between thecourse of the determined second lane marking and the course of movementof the vehicle driving ahead. The lane marking that has a higher degreeof correspondence will then be selected as valid lane marking. Here itis advantageous to select the lane marking with the highest degree ofcorrespondence as the relevant lane marking only when it has a minimumdegree of correspondence and/or when the difference between the firstdegree and the second degree exceeds a preset minimum difference.

It is particularly advantageous when a lane departure warning system isprovided with the course of the lane marking determined as the validlane marking or with an information on the lane marking selected as thevalid lane marking. The driver assistance system then takes the courseof the determined valid lane marking into account as the lane marking tobe followed. The lane departure warning system can in particular be alane change assistance system.

In addition, the position of the own vehicle relative to the first lanemarking and relative to the second lane marking may be determined,preferably repeatedly.

The determined position or the determined positions are taken intoaccount in the selection of the relevant lane marking. In particular,the determined positions of the vehicle driving ahead and/or of the ownvehicle, the determined courses of the detected lane markings and/or thesteering movement or the yaw rate of the own vehicle may be fed to aclassifier which then determines the relevant lane marking on the basisof these input variables.

It is particularly advantageous to determine the position of the ownvehicle relative to the first lane marking and relative to the secondlane marking several times, to determine the course of movement of theown vehicle on the basis of these determined positions and to take thiscourse of movement into account in the selection of the valid lanemarkings, for example as an input variable for a classifier fordetermining the valid lane marking. The course of movement of the ownvehicle can be determined with the aid of the steering angle and thespeed of the own vehicle.

The device of the independent device claim can be developed in the samemanner as the inventive method, in particular by the features specifiedin the dependent claims or by respective device features.

Further features and advantages of the invention result from thefollowing description, which in connection with the attached Figuresexplains the invention in more detail with reference to embodiments.

FIG. 1 shows a side view of a schematic illustration of a vehicle in atraffic situation, the vehicle having a device for capturing andprocessing pictures.

FIG. 2 shows the illustration of a first picture captured with the aidof the device, in which picture a vehicle driving ahead is imaged.

FIG. 3 is an illustration of a second picture captured with the aid ofthe device, in which picture the vehicle driving ahead and a permanentlane marking as well as a temporary lane marking are imaged.

FIG. 4 is the illustration of a third picture captured with the aid ofthe device, in which picture the vehicle driving ahead and the permanentlane marking as well as the temporary lane marking are imaged.

FIG. 5 is a block diagram with components of the device for capturingand processing pictures according to FIG. 1.

In FIG. 1, a side view of a vehicle 12 is shown in a traffic situation10 during the travel of the vehicle 12 along a lane 14. The vehicle 12has a camera system with at least one camera 17. In the presentembodiment, the camera system 16 is a mono camera system and ablack-and-white camera system for capturing gray scale pictures. Thecamera system 16 captures a picture series of pictures with images of adetection area in front of the vehicle 12. The horizontal detection areais schematically illustrated in FIG. 1 by the broken lines 18, 20.Further, image data corresponding to the pictures are generated. Thegenerated image data are transferred from the camera system 16 to aprocessing unit 22 arranged in the vehicle 12, which unit processesthese data. In particular, the image data are processed in theprocessing unit 22 to provide a driver assistance system for the driverof the vehicle 12. The picture-taking rate of the camera 17 of thecamera system 16 is preferably 10 to 50 pictures per second. Thepictures are continuously taken by the camera at this rate and arecontinuously processed by the processing unit 22.

The image data of an object 28 generated by the camera system 16 areprocessed by the processing unit 22, the image of the object 28 beingdetected as an object image or as an object, and preferably the objecttype of the object 28 being classified. In the same manner, trafficsigns, lane indicators, street lights, vehicles driving ahead on thelane 14 and oncoming vehicles on an oncoming lane may be detected asobjects and their object type may be classified. In particular, theposition of the images of the objects 28 detected in the picture isdetermined and compared to the position of the images of the sameobjects 28 in a following picture of the picture series. Forsimplification, the position of an image of an object in a picture isbriefly referred to in the following as the position of the object inthe picture or as the picture position of the object. The comparison ofthe position of objects 28 in a first picture and a second picture takenafter this first picture is for example used to influence the drivingbehavior and/or to provide the driver of the vehicle 12 with definedinformation on the environment and on the own vehicle 12. Thisinformation can for example also serve as input data for driverassistance systems, in particular for a lane change assistance system.

In FIG. 2, a first picture 30 of the detection area of the camera 17 infront of the vehicle 12 taken with the aid of the camera 17 is shown. Inthe picture 30, the horizon is-illustrated as a solid line 32. Further,the picture comprises an image of a vehicle driving ahead 34, images oflane markings 36 to 42 and images of guard rails 44, 46 arrangedlaterally next to the outer lanes as well as traffic signs 48, 50arranged laterally next to the lane. In FIG. 2, the lane markings 36 to42 are merely schematically illustrated as solid lines. Actually, theymay also be present in the form of broken lines and, for a betterrecognition, have a slightly larger width. In the picture 30, an arrow52 is illustrated which indicates the direction of travel of the ownvehicle as well as the direction of travel of the vehicle driving ahead.The starting point P1 of the arrow 52 is the position of the vehicledriving ahead 34 which has been determined in a preceding picture of apicture series taken of the detection area in front of the vehicle 12with the aid of the camera 17. The end point P4 applies to the vehicledriving ahead 34 based on the position determined in the picture 30shown in FIG. 2. Between the picture, based on which the position P1 hasbeen determined, and the picture 30 a plurality of further pictures mayhave been taken with the aid of the camera 17. The image data of atleast a part of these pictures have likewise been processed, or theposition of the vehicle driving ahead 34 may have been determinedrepeatedly but not necessarily.

In FIG. 3, a further picture 54 taken with the aid of the camera 17 isillustrated. In addition to the elements illustrated in the picture 30according to FIG. 2, the picture 54 comprises images of temporary lanemarkings 56, 58. Further, images of roadworks 60 and of a roadconstruction barrier 62 can be seen in the picture 54. The lane definedwith the aid of the temporary lane markings 56, 58 deviates from thecourse of the lane delimited by the lane markings 38, 40 so that thetraffic is diverted from this lane to the lane delimited by the markings40, 42. For a simplified illustration, the pictures 30 and 54 onlydiffer from one another by the additionally present lane markings 56,58, the roadworks 60, 62 and the position of the vehicle driving ahead34. For simplification of the following explanations, the arrow 52 islikewise illustrated in the picture 54 according to FIG. 3. In addition,an arrow 64 is illustrated which indicates several positions P1 to P4 ofthe vehicle driving ahead 34 and thus shows the course of movement ofthe vehicle 34. In a first picture taken before the picture 54, theposition P1 of the vehicle driving ahead 34 has been determined. In apicture taken after this first picture, but taken before the picture 54,the position P2 of the vehicle driving ahead 34 has been determined. Ina third picture taken before the picture 54, the position P3 of thevehicle driving ahead 34 has been determined. In picture 54, theposition P4 of the vehicle driving ahead 34 has been determined. Byconnecting these determined positions, there results the arrow 64 whichthus indicates the course of movement of the vehicle driving ahead 34between the position P1 and the position P4. Between the shots of thefirst and the second picture, between the shots of the second and thethird picture, and between the shots of the third picture and thepicture 54, a large number of further pictures may have been taken andevaluated. The determined course of movement of the vehicle drivingahead 34 illustrated by the arrow 64 thus runs substantially parallel tothe temporary lane markings 56, 58 and widely differs from the course ofthe lane markings 38, 40. The course of movement of the vehicle drivingahead 34 indicated by the arrow 64 intersects the original lane marking40 between the position P3 and P4. As a result of the highercorrespondence of the determined course of movement of the vehicledriving ahead 34 with the temporary lane markings 56, 58 compared to thepermanent lane markings 38, 40, the lane markings 56, 58 are determinedas valid lane markings 56, 58 and provided as relevant or valid lanemarkings 56, 58 for a driver assistance system. If, however, aspositions for the vehicle driving ahead the positions P1, P2*, P3* andP4* had been determined in several successively taken pictures, a courseof movement of the vehicle driving ahead 34 that is parallel to the lanemarkings 38, 40 is determined by means of these positions P1, P2*, P3*,P4*. This course of movement then intersects the lane marking 56. Thecourse of movement marked by the arrow 52 would thus correspond to thecourse of the lane markings 38, 40 so that these lane markings 38, 40could then be used as valid lane markings.

Other factors however may as well be used in the determination of thevalid lane marking or in the verification of a determined valid lanemarking. In particular, warning barriers 62 arranged transversely to thelane can be used for determining or verifying a determined valid lanemarking. Also the position of the own vehicle 12, a steering angle ofthe vehicle 12 or a yaw angle of the vehicle 12 as well as the speed ofthe vehicle 12 can be taken into account in the determination orverification of the valid lane marking.

In general, the behavior of an existing vehicle driving ahead 34 isobserved and is taken into account in the selection of the valid lanemarking. Additionally or alternatively, the driving behavior of the ownvehicle 12 can be taken into account in the determination of a validlane marking.

It can be assumed that a vehicle 12, 34 drives approximately in thecenter of a valid lane, this being true both for the vehicle drivingahead 34 and the own vehicle 12. With the aid of the described approach,the valid lane marking can easily be determined in the case ofoverlapping lane markings. Such overlapping lane markings in particularoccur in the case of temporary lane markings 56, 58 that are applied tothe lane 14 in addition to already present lane markings 36 to 42. Thismay in particular be necessary when roadworks 60 require the closing offof at least one lane. When, by analyzing the course of movement 54, itis determined that the vehicle driving ahead 34 relatively abruptlychanges its direction before it enters an area of roadworks 60, as thisis shown in FIG. 3, then the driver assistance system may conclude atransfer to the lane with the lane markings 56, 58 on the basis of theabrupt change of the direction of travel of the vehicle driving ahead 34by way of a comparison of the change in position of the vehicle drivingahead 34 in several successively taken pictures. The lane delimited bythe lane markings 56, 58 is also referred to as construction zone lane.

In FIG. 4, a further picture 66 taken with the aid of the camera 17 isshown, in which the vehicle driving ahead 34 is located in front of thevehicle 12. By way of the lateral distance between the vehicle drivingahead 34 and the temporary lane markings 56, 58, these are stilldetected as relevant lane markings or as valid lane markings. Thepermanent lane marking 40 is still detected as non-valid lane marking.

In general, according to the invention an information for interpretationand for determination of the own lane is determined with the aid of adetected vehicle driving ahead 34, on the basis of which information avalid lane marking or valid lane is determined from several differentlane markings or lanes. It is particularly advantageous to take the ownmovement of the vehicle 12 into account in the determination of thevalid lane.

In FIG. 5, a block diagram with the processing unit 22 and the camerasystem 16 is shown, with the aid of which a valid lane marking isselected or the original selection of these lane markings 56, 58 asvalid lane markings 56, 58 is confirmed. The processing unit 22comprises a central processing unit (CPU) 78, a data bus 80 and threestorage elements 82 to 86.

The processing unit 22 is connected to the camera system 16 via a firstinterface 76. Further, the processing unit 22 comprises a secondinterface 88, via which the data processed with the aid of theprocessing unit 22 can be output to other elements, for example thelight control module 24. Preferably, the second interface 88 forms aconnection to a vehicle bus system.

The CPU 78, the first interface 76, the second interface 88 and thestorage elements 82, 84, 86 are connected to one another via the databus 80. The image data corresponding to the pictures 44 a to 44 c, 52generated with the aid of the camera system 16 are transmitted via thefirst interface 76 from the camera system 16 to the processing unit 22as input data. The image data are stored in the first storage element82. In the second storage element 84 of the processing unit at leastprogram data of at least one image processing program for determiningthe image positions P1 to P4, P1 to P4* are stored. Likewise, in thesecond storage element 84 program data of a routine for determining avalid lane and/or valid lane markings 56, 58 based on the determinedimage positions P1 to P4 and the course of detected lane markings 36 to42, 56, 58 are stored.

The determined change in position of the vehicle driving ahead 34between pictures successively taken with the aid of the camera 17 isthen used as an input variable for a lane change assistance systemand/or output via the second interface 88. Such a lane change assistancesystem is also referred to as a lane departure warning system.

The invention is described in connection with a mono camera forcapturing gray level pictures. However, the invention may likewise beused in the same manner in a stereo camera system and/or in colorcameras.

1. A method for determining a valid lane marking with the aid of acamera system of a vehicle, in particular a road vehicle, in which withthe aid of a camera (17) of the camera system (16) several pictures (30,54, 66) with images of an area in front of the vehicle (12) aresuccessively taken as a picture series, and image data corresponding tothe respective picture (30, 54, 66) are generated, and in which theimage data of at least a part of the pictures (30, 54, 66) of thepicture series are processed, wherein at least a first lane marking (38,40) and a second lane marking (56, 58) different from the first lanemarking are detected in at least one picture of the picture series, avehicle (34) driving ahead of the vehicle (12) is detected in at leasttwo successively taken pictures (30, 54, 66) of the picture series, foreach of the at least two pictures, the position (P1 to P4; P1 to P4*) ofthe vehicle driving ahead (34) relative to the first lane marking (38,40) and the position (P1 to P4; P1 to P4*) of the vehicle driving ahead(34) relative to the second lane marking (56, 58) is determined, andwherein, dependent on the positions (P1 to P4; P1 to P4*) of the vehicledriving ahead (34) determined with the aid of the pictures, one of thedetected lane markings (38, 40; 56, 58) is selected as the valid lanemarking.
 2. The method according to claim 1, characterized in that basedon at least two, preferably at least three of the pictures successivelytaken as a picture series, a course of movement (52, 64) of the vehicledriving ahead (34) is determined, and in that based on the determinedcourse of movement (52, 64) of the vehicle driving ahead (34) and thecourses of the at least two detected lane markings (38, 40; 56, 58) oneof the lane markings (38, 40; 56, 58) is selected as the valid lanemarking.
 3. The method according to one of the preceding claims,characterized in that from the at least two lane markings (38, 40; 56,58) the lane marking (38, 40; 56, 58) is selected as the valid lanemarking (38, 40) that, for both determined positions, has a lateraloffset transverse to the traffic direction of the lane (14) that iswithin a preset range for both positions (P1 to P4; P1 to P4*), or towhich the determined positions (P1 to P4; P1 to P4*) have smallerlateral distances.
 4. The method according to one of the precedingclaims, characterized in that a crossing of at least one of the detectedlane markings (38, 40; 56, 58) is detected and is taken into account inthe determination of the valid lane marking (38, 40; 56, 58).
 5. Themethod according to one of the preceding claims, characterized in that afirst degree of correspondence between the course of the firstdetermined lane marking (38, 40) and the course of movement (52, 64) ofthe vehicle driving ahead (34) and a second degree of correspondencebetween the course of the second determined lane marking (56, 58) andthe course of movement (52, 64) of the vehicle driving ahead (34) isdetermined, and in that the lane marking (38, 40; 56, 58) that has ahigher degree of correspondence is selected as the valid lane marking.6. The method according to claim 5, characterized in that the lanemarking (38, 40; 56, 58) with the highest degree of correspondence isselected as the valid lane marking (38, 40; 56, 58) only when the degreeof correspondence has a minimum degree of correspondence and/or when thedifference between the first degree and the second degree exceeds apreset minimum difference.
 7. The method according to one of thepreceding claims, characterized in that a lane departure warning systemis provided with the course of the lane marking (38, 40; 56, 58)determined as the valid lane marking or with an information on the lanemarking (38, 40; 56, 58) selected as the valid lane marking, and in thatthe driver assistance system processes the course of the valid lanemarking (38, 40; 56, 58) as the lane marking (38, 40; 56, 58) to befollowed.
 8. The method according to one of the preceding claims,characterized in that in addition the position of the own vehicle (12)relative to the first lane marking (38, 40) and relative to the secondlane marking (56, 58) is determined, preferably repeatedly, and in thatthe determined position is taken into account in the selection of thevalid lane marking (38, 40; 56, 58).
 9. The method according to claim 8,characterized in that the position of the own vehicle (12) relative tothe first lane marking (38, 40) and relative to the second lane marking(56, 58) is determined several times, and the course of movement of theown vehicle (12) is taken into account in the selection of the validlane marking (38, 40; 56, 58).
 10. The method according to claim 9,characterized in that the course of movement (52, 64) of the own vehicle(12) is determined with the aid of the steering angle and the speed ofthe own vehicle (12).
 11. A device for determining a valid lane markingwith the aid of a camera system (16) of a vehicle (12), in particular aroad vehicle, with a camera system (16) having a camera (17) forsuccessively taking several pictures (30, 54, 66) with images of an areain front of the vehicle (12) as a picture series and generating imagedata corresponding to the respective picture (30, 54, 66), with aprocessing unit (22) for processing the image data of at least a part ofthe pictures (30, 54, 66) of the picture series, wherein the processingunit (22) detects in at least one picture (30, 54, 66) of the pictureseries at least two different lane markings (38, 40; 56, 58), theprocessing unit (22) detects a vehicle (34) driving ahead of the vehicle(12) in at least two pictures (30, 54, 66) of the picture series andeach time determines the position (P1 to P4; P1 to P4*) of the vehicledriving ahead (34) relative to the detected first lane marking (38, 48;56, 58) and the position of the vehicle relative to the second lanemarking for each of the at least two pictures, and wherein theprocessing unit (22), dependent on the determined positions (P1 to P4;P1 to P4*) of the vehicle driving ahead (34) relative to both lanemarkings (38, 40; 56, 58), selects one of these detected lane markings(38, 40; 56, 58) as the valid lane markings (56, 58).